<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript">
        /*静态注册*/
        var onchangeFunc = function () {
            console.log("静态注册");
        }

        /*动态注册*/
        window.onload = function () {
            var country1 = document.getElementById("country1");
            country1.onchange = function () {
                console.log("动态注册");
            }
        }
    </script>
</head>
<body>
<select name="country" id="country" onchange="onchangeFunc()">
    <option value="default">--请选择--</option>
    <option value="cn">中国</option>
    <option value="us">美国</option>
    <option value="jp">日本</option>
</select>
<select name="country1" id="country1" onchange="onchangeFunc()">
    <option value="default">--请选择--</option>
    <option value="cn">中国</option>
    <option value="us">美国</option>
    <option value="jp">日本</option>
</select>
</body>
</html>